Electrical Inspector : You Make The Call!

[jar546]

As an electrical inspector, you are reviewing the electrical plans of a new commercial building. During your inspection, you notice a branch circuit designed to supply a combination of continuous and noncontinuous loads. According to the plans, the continuous load on this circuit is 20 amps, and the noncontinuous load is 10 amps. Your job is to ensure that the overcurrent protective device for this circuit is correctly sized according to NEC 210.20(A).

Question for the Electrical Inspector: Based on NEC 210.20(A), which of the following actions would you take regarding the sizing of the overcurrent protection device for this branch circuit?

A. Approve a 30-amp overcurrent protection device, as it matches the sum of continuous and noncontinuous loads.

B. Suggest a 35-amp overcurrent protection device, since it provides a margin above the combined load.

C. Require a minimum 35-amp overcurrent protection device, calculated as the noncontinuous load (10 amps) plus 125 percent of the continuous load (20 amps x 125% = 25 amps; 10 amps + 25 amps = 35 amps).

D. Recommend a 40-amp overcurrent protection device to ensure ample capacity for potential load increases.

 

[TheCommish]

Change the wire size also to carry the additional current

 

[Inspector Gadget]

I am not an electrical guy, buuuuuuut I'm fully aware of inductive loading for motors, and that has me thinking the correct answer is not 30.

 

[ICE]

None of the choices are correct. Providing a copy of the code section and allowing the applicant to decide how to meet the code is the correct response.

210.20(A) Continuous and Noncontinuous Loads.
Where a branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the rating of the overcurrent device shall not be less than the noncontinuous load plus125 percent of the continuous load.

Exception: Where the assembly, including the overcurrent devices protecting the branch circuit(s), is listed for operation at 100 percent of its rating, the ampere rating of the overcurrent device shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load.